Welcome to the forum "pafman" .. Lots of good folks here will be able to help you with your button, but we will need more photos and more information about the button itself. Thanks
Found in farm in Massachusetts
Front has eagle on anchor and has thirteen stars around it and three dots under the eagle and looks like a rope around whole design and goes through the front of anchor ring
Back is rusted can't identify anything possibly a steel back
Front of button is non magnetic
Back of button is magnetic
I am fairly certain that your button, having a tin back, is actually a more modern day fashion button. There have been a lot of discussions about this very button here on the T-Net .. I will see if I can find a link to some .. They are some fascinating reading.